Auto-format Framework (#160545)

This auto-formats all *.dart files in the repository outside of the
`engine` subdirectory and enforces that these files stay formatted with
a presubmit check.

**Reviewers:** Please carefully review all the commits except for the
one titled "formatted". The "formatted" commit was auto-generated by
running `dev/tools/format.sh -a -f`. The other commits were hand-crafted
to prepare the repo for the formatting change. I recommend reviewing the
commits one-by-one via the "Commits" tab and avoiding Github's "Files
changed" tab as it will likely slow down your browser because of the
size of this PR.

---------

Co-authored-by: Kate Lovett <katelovett@google.com>
Co-authored-by: LongCatIsLooong <31859944+LongCatIsLooong@users.noreply.github.com>

.vscode/settings.json

@@ -1,15 +1,6 @@
 // VSCode workspace settings that are shared among all users of this project.
 // This only affects subdirectories of this project.
 {
-    // VSCode formats files on save by default. Since Flutter source code is
-    // hand-formatted, the default settings are changed to prevent inadvertent
-    // reformatting of code.
-    "[dart]": {
-        "editor.formatOnSave": false,
-        "editor.formatOnType": false,
-        "editor.formatOnPaste": false,
-    },
-
     "html.format.enable": false,
     "githubPullRequests.ignoredPullRequestBranches": [
         "master"